<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var a = "haha";
        var b = 'hehe';
        // var c = hehe;    // 运行出错 ---》要拿单双引号包裹起来
        //var msg = "My name is "zhangsan"";    //错误
        // var msg = "My name is 'zhangsan'";    // 正确, 搭配使用单双引号
        // var msg = 'My name is "zhangsan"';    // 正确, 搭配使用单双引号
        if(10 == '10') console.log("==");       //会进行隐式类型转换
        if(10 === '10') console.log("===");     //不会进行隐式类型转换
        //长度
        console.log(a.length);
        //拼接

        console.log('100' + 100); // 100100
    </script>
</body>
</html>